Antioxidant combination for oxidation and deposit control in lubricants containing molybdenum and alkylated phenothiazine

ABSTRACT

The invention relates to a lubricating oil composition having improved antioxidant properties, and which contains a molybdenum compound and an alkylated phenothiazine. Further, it may also include a secondary diarylamine, preferably an alkylated diphenylamine. This combination of additives provides improved oxidation control and friction modifier performance to the lubricating oil. The composition is particularly suited for use as a crankcase lubricant, or a transmission lubricant, including low levels and zero levels of phosphorus.

RELATED APPLICATIONS

This application is a continuation in part of U.S. application Ser. No.10/858,410 (dkt 7391/84052), filed Jun. 2, 2004 and of U.S. applicationSer. No. 10/158,096, filed May 30, 2002, the complete disclosures ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to lubricating oil compositions, their method ofpreparation, and use. More specifically, this invention relates tolubricating oil compositions which contain a molybdenum compound and analkylated phenothiazine. The composition may further contain a secondarydiarylamine. The use of both the molybdenum and the alkylatedphenothiazine, and alternatively further with the secondary diarylamine,provides improved oxidation and deposit control to lubricating oilcompositions. The lubricating oil compositions of this invention areparticularly useful as crankcase and transmission lubricants.

2. Description of the Related Art

Lubricating oils as used in the internal combustion engines andtransmissions of automobiles or trucks are subjected to a demandingenvironment during use. This environment results in the oil sufferingoxidation which is catalyzed by the presence of impurities in the oilsuch as iron compounds and is also promoted by the elevated temperaturesof the oil during use.

The oxidation of lubrication oils during use is usually controlled tosome extent by the use of antioxidant additives which may extend theuseful life of the lubricating oil, particularly by reducing orpreventing unacceptable viscosity increases. Aminic antioxidants areantioxidants that contain one or more nitrogen atoms. An example of anaminic antioxidant is phenothiazine. The prior art discloses the manyteachings on the synthesis and uses of phenothiazine. Phenothiazineantioxidants have been used as a stand alone additive, chemicallymodified or grafted onto the backbone of polymers.

Lubricant compositions containing various molybdenum compounds andaromatic amines have been used in lubricating oils. Such compositionsinclude active sulfur or phosphorous as part of the molybdenum compound,use additional metallic additives, various amine additives which aredifferent from those used in this invention, and/or have concentrationsof molybdenum and amine which do not show the synergistic resultsobtained by this invention.

An interesting trend in the lubricant industry is a shift to lower andlower phosphorus levels. Thus, at some point the industry will requirelubricant formulations for crankcase and transmission fluids, bothautomatic and manual, with zero or essentially zero phosphorus content.

Existing lubricants employing phenothiazine are taught in U.S. Pat. No.5,614,124 and references cited therein, all of which are incorporatedherein in their entirety by reference.

SUMMARY OF THE INVENTION

This invention relates to lubricating oil compositions, their method ofpreparation, and use. More specifically, this invention relates tolubricating oil compositions which contain a molybdenum compound and analkylated phenothiazine. The composition may further contain a secondarydiarylamine. The use of both the molybdenum and the alkylatedphenothiazine, and alternatively further with the secondary diarylamine,provides improved oxidation and deposit control to lubricating oilcompositions. The lubricating oil compositions of this invention areparticularly useful as crankcase and transmission lubricants.

DETAILED DESCRIPTION OF THE INVENTION

It has been found that the combination of (1) an oil soluble molybdenumcompound and (2) an alkylated phenothiazine, and also preferably asecondary diarylamine, such as an alkylated diphenylamine, is highlyeffective at controlling crankcase lubricant oxidation and depositformation. Examples of the types of compounds that may be used in thisinvention are described in the following. The alkylated diphenylamine(preferred secondary diarylamine) may be used at concentrations rangingfrom 0.1 to 2.5 wt. % in the finished lubricant, preferably between 0.2to 1.5 wt. %. The molybdenum compound may be used between 20 and 1000ppm, preferably between 20 to 200 ppm, based on the amount of molybdenumdelivered to the finished lubricating oil. In an embodiment of thelubricating composition, the molybdenum compounds are free oftri-nuclear molybdneum compounds and more particularly free of thetri-nuclear compounds according to U.S. Pat. No. 6,358,894. Theexpression “free of tri-nuclear molybdenum compounds” includes beingfree of such compounds according to U.S. Pat. No. 6,358,894, which canbe stated as provided that the oil soluble molybdenum compound is not atri-nuclear molybdenum compound. The alkylated phenothiazine may be usedat concentrations ranging from 0.05 to 1.5 wt. % in the finishedlubricant, preferably between 0.1 to 1.0 wt. %. In addition to theantioxidants of this invention, the lubricating composition may alsocontain dispersants, detergents, anti-wear additives including forexample ZDDP, additional antioxidants if required, friction modifiers,corrosion inhibitors, anti-foaming additives, pour point depressants andviscosity index improvers. The lubricant may be prepared from anyparaffinic, naphthenic, aromatic, or synthetic base oil, or mixturesthereof. In an embodiment, the lubricant may contain between 250 and1000 ppm of phosphorus derived from ZDDP and between 500 and 3000 ppm ofcalcium from calcium containing sulfonate detergents or calciumcontaining phenate detergents. In this manner, both crankcase andautomatic transmission fluid (ATF) lubricants are readily prepared.

Thus, in an embodiment of the present invention is provided crankcaseand transmission fluid lubricants and additive package concentratestherefor, which contain very low levels of phosphorus. More preferred,are lubricant compositions containing zero or essentially zerophosphorus. By “essentially zero phosphorus” herein is meant phosphoruslevels of less than or equal to about 100 ppm.

In another embodiment, the lubricant does not contain ZDDP, but maycontain other sources of phosphorus.

I. Molybdenum Compounds

1. Sulfur- and Phosphorus-Free Organomolybdenum Compound

A sulfur- and phosphorus-free organomolybdenum compound that is acomponent of the present invention may be prepared by reacting a sulfurand phosphorus-free molybdenum source with an organic compoundcontaining amino and/or alcohol groups. Examples of sulfur- andphosphorus-free molybdenum sources include molybdenum trioxide, ammoniummolybdate, sodium molybdate and potassium molybdate. The amino groupsmay be monoamines, diamines, or polyamines. The alcohol groups may bemono-substituted alcohols, diols or bis-alcohols, or polyalcohols. As anexample, the reaction of diamines with fatty oils produces a productcontaining both amino and alcohol groups that can react with the sulfur-and phosphorus-free molybdenum source.

Examples of sulfur- and phosphorus-free organomolybdenum compoundsappearing in patents and patent applications which are fullyincorporated herein by reference include the following:

1. Compounds prepared by reacting certain basic nitrogen compounds witha molybdenum source as defined in U.S. Pat. Nos. 4,2959,195 and4,261,843.

2. Compounds prepared by reacting a hydrocarbyl substituted hydroxyalkylated amine with a molybdenum source as defined in U.S. Pat. No.4,164,473.

3. Compounds prepared by reacting a phenol aldehyde condensationproduct, a mono-alkylated alkylene diamine, and a molybdenum source asdefined in U.S. Pat. No. 4,266,945.

4. Compounds prepared by reacting a fatty oil, diethanolamine, and amolybdenum source as defined in U.S. Pat. No. 4,889,647.

5. Compounds prepared by reacting a fatty oil or acid with2-(2-aminoethyl)aminoethanol, and a molybdenum source as defined in U.S.Pat. No. 5,137,647.

6. Compounds prepared by reacting a secondary amine with a molybdenumsource as defined in U.S. Pat. No. 4,692,256.

7. Compounds prepared by reacting a diol, diamino, or amino-alcoholcompound with a molybdenum source as defined in U.S. Pat. No. 5,412,130.

8. Compounds prepared by reacting a fatty oil, mono-alkylated alkylenediamine, and a molybdenum source as defined in European PatentApplication EP 1 136 496 A1.

9. Compounds prepared by reacting a fatty acid, mono-alkylated alkylenediamine, glycerides, and a molybdenum source as defined in EuropeanPatent Application EP 1 136 497 A1.

Examples of commercial sulfur- and phosphorus-free oil solublemolybdenum compounds are Sakura-Lube 700 from Asahi Denka Kogyo K.K.,and Molyvan® 856B and Molyvan® 855 from R T. Vanderbilt Company, Inc.

Molybdenum compounds prepared by reacting a fatty oil, diethanolamine,and a molybdenum source as defined in U.S. Pat. No. 4,889,647 aresometimes illustrated with the following structure, where R is a fattyalkyl chain, although the exact chemical composition of these materialsis not fully known and may in fact be multi-component mixtures ofseveral organomolybdenum compounds

II. Sulfur-Containing Organomolybdenum Compound

The sulfur-containing organomolybdenum compound useful in the presentinvention may be prepared by a variety of methods. One method involvesreacting a sulfur and phosphorus-free molybdenum source with an aminogroup and one or more sulfur sources. Sulfur sources can include forexample, but are not limited to, carbon disulfide, hydrogen sulfide,sodium sulfide and elemental sulfur. Alternatively, thesulfur-containing molybdenum compound may be prepared by reacting asulfur-containing molybdenum source with an amino group or thiuram groupand optionally a second sulfur source. Examples of sulfur- andphosphorus-free molybdenum sources include molybdenum trioxide, ammoniummolybdate, sodium molybdate, potassium molybdate and molybdenum halides.The amino groups may be monoamines, diamines, or polyamines. As anexample, the reaction of molybdenum trioxide with a secondary amine andcarbon disulfide produces molybdenum dithiocarbanates. Alternatively,the reaction of (NH₄)₂Mo₃S₁₃*n(H₂O) where n vanes between 0 to 2, with atetralkylthiuram disulfide, produces a trinuclear sulfur-containingmolybdenum dithiocarbamate.

Examples of sulfur-containing organomolybdenum compounds appearing inpatents and patent applications include the following:

1. Compounds prepared by reacting molybdenum trioxide with a secondaryamine and carbon disulfide as defined in U.S. Pat. Nos. 3,509,051 and3,356,702.

2. Compounds prepared by reacting a sulfur-free molybdenum source with asecondary amine, carbon disulfide, and an additional sulfur source asdefined in U.S. Pat. No. 4,098,705.

3. Compounds prepared by reacting a molybdenum halide with a secondaryamine and carbon disulfide as defined in U.S. Pat. No. 4,178,258.

4. Compounds prepared by reacting a molybdenum source with a basicnitrogen compound and a sulfur source as defined in U.S. Pat. Nos.4,263,152, 4,265,773, 4,272,387, 4,285,822, 4,369,11.9, 4,395,343.

5. Compounds prepared by reacting ammonium tetrathiomolybdate with abasic nitrogen compound as defined in U.S. Pat. No. 4,283,295.

6. Compounds prepared by reacting an olefin, sulfur, an amine and amolybdenum source as defined in U.S. Pat. No. 4,362,633.

7. Compounds prepared by reacting ammonium tetrathiomolybdate with abasic nitrogen compound and an organic sulfur source as defined in U.S.Pat. No. 4,402,840.

8. Compounds prepared by reacting a phenolic compound, an amine and amolybdenum source with a sulfur source as defined in U.S. Pat. No.4,466,901.

9. Compounds prepared by reacting a triglyceride, a basic nitrogencompound, a molybdenum source, and a sulfur source as defined in U.S.Pat. No. 4,765,918.

10. Compounds prepared by reacting alkali metal alkylthioxanthate saltswith molybdenum halides as defined in U.S. Pat. No. 4,966,719.

11. Compounds prepared by reacting a tetralkylthiuram disulfide withmolybdenum hexacarbonyl as defined in U.S. Pat. No. 4,978,464.

12. Compounds prepared by reacting an alkyl dixanthogen with molybdenumhexacarbonyl as defined in U.S. Pat. No. 4,990,271.

13. Compounds prepared by reacting alkali metal alkylxanthate salts withdimolybdenum tetra-acetate as defined in U.S. Pat. No. 4,995,996.

14. Compounds prepared by reacting (NH₄)₂Mo₃S₁₃*₂H₂O with an alkalimetal dialkyldithiocarbamate or tetralkyl thiuram disulfide as define inU.S. Pat. No. 6,232,276.

15. Compounds prepared by reacting an ester or acid with a diamine, amolybdenum source and carbon disulfide as defined in U.S. Pat. No.6,103,674.

16. Compounds prepared by reacting an alkali metaldialkyldithiocarbamate with 3-chloropropionic acid, followed bymolybdenum trioxide, as defined in U.S. Pat. No. 6,117,826.

Examples of commercial sulfur-containing oil soluble molybdenumcompounds are Sakura-Lube 100, Sakura-Lube 155, Sakura-Lube 165, andSakura-Lube 180 from Asahi Denka Kogyo K.K., Molyvan(t A, Molyvan® 807and Molyvan® 822 from R. T. Vanderbilt Company, and Naugalube MolyFMfrom Crompton Corporation.

Molybdenum dithiocarbamates are illustrated with the followingstructure, where R is an alkyl group containing 4 to 18 carbons or H,and X is O or S.

II. Alkylated Phenothiazine

An alkylated phenothiazine suitable for this invention must be oilsoluble or dispersible and correspond to the general formula belowwherein R₁ is a linear or branched C₄-C₂₄ alkyl, heteroalkyl oralkylaryl group and R₂ is H or a linear or branched C₄-C₂₄ alkyl,heteroalkyl or alkylaryl group.

Typical examples of alkylphenothiazine include but are not limited tomonotetradecylphenothiazine, ditetradecylphenothiazine,monodecylphenothiazine, didecylphenothiazine monononylphenothiazine,dinonylphenothiazine, monoctylphenothiazine and dioctylphenothiazine.

General Preparation of an Alkylphenothiazine

Non-limiting examples of the preparation of alkylphenothiazine arementioned in U.S. Pat. Nos. 5,614,124 and 2,781,318.

Diphenylamine can be alkylated with an olefin in the presence of acatalyst. Typical catalysts are acid clay or AlCl₃. Thealkyldiphenylamine can then be sulfurized in the presence of asulfurizing agent and a catalyst. The preferred sulfur reagent andcatalyst are elemental sulfur and iodine, respectively. Non-limitingother sulfurization catalysts are aluminum bromide, aluminum chloride,copper iodide, sulfur iodide, antimony chloride or Iron (III) chloride.

Thus, the alkyldiphenylamine can be of any structure so long as itcontains at least one nitrogen atom, two aromatic rings such that eacharomatic ring has at least one open ortho position to effectsulfurization and be oil soluble. A partial list of non-limitingalkyldiphenylamines suitable for sulfurization includes:monoctyldiphenylamine, dioctyldiphenylamine, monononyldiphenylamine,dinonyldiphenylamine, monodecyldiphenylamine, didecyldiphenylamine,monotetradecyldiphenylamine, ditetradecyldiphenylamine as well asvarious mixtures and combinations of these alkyldiphenylamines. Names ofcommercial alkyldiphenylamines suitable for use with this invention areNaugalube N-438L, manufactured by CK Witco, and Goodrite 0.3190NT,manufactured by Noveon.

EXAMPLE 1 C₁₄ Alkylphenothiazine Synthesis

Into a round bottom flask equipped with a stirrer, reflux condenser,thermometer, thermocouple and nitrogen gas inlet tube are added thefollowing: C₁₄ alkyldiphenylamine (374 gms, 0.680 mols), elementalsulfur (65 gms, 2.04 mols), iodine (5.7 gms, 0.022 mols) and xylenes(344 ml). Nitrogen gas was bubbled into the reaction mixture at 200ml/min and with vigorous agitation the reaction mixture was cooked at140 C. for 4 hours. The product was stripped of solvent and iodine toyield 396 gms of product. Found analytical data: wt. % N=2.9, wt. %S=7.89 and 100 C. KV=31.43.

EXAMPLE 2 Mixed Mono and Di-C₉ Alkylphenothiazine Synthesis

Into a round bottom flask equipped with a stirrer, reflux condenser,thermometer, thermocouple and nitrogen gas inlet tube are added thefollowing: C₉ alkyldiphenylamine (264.9 gms, 0.680 mols), elementalsulfur (65 gms, 2.04 mols), iodine (5.7 gms, 0.022 mols), base oil(286.7 gms) and xylenes (344 ml). Nitrogen gas was bubbled into thereaction mixture at 200 ml/min and with vigorous agitation the reactionmixture was cooked at 140 C. for 4 hours. The product was stripped ofsolvent and iodine to yield 533 gms of product. Found analytical data:wt. % N=1.56, wt. % S=5.45, and 100 C. KV=30.0.

III. Alkylated Diarylamine

The diarylamines that may optionally be used, and that have been foundto be useful in this invention are well known antioxidants and there isno known restriction on the type of diarylamine that can be used.Preferably, the diarylamine has the formula:

-   -   wherein R′ and R″ each independently represents a substituted or        unsubstituted aryl group having from 6 to 30 carbon atoms.        Illustrative of substituents for the aryl group include        aliphatic hydrocarbon groups such as alkyls having from 1 to 30        carbon atoms, hydroxy groups, halogen radicals, carboxylic acid        or ester groups, or nitro groups. The aryl is preferably        substituted or unsubstituted phenyl or naphthyl, particularly        wherein one or both of the aryl groups are substituted with at        least one alkyl having from 4 to 30 carbon atoms, preferably        from 4 to 18 carbon atoms, most preferably from 4 to 9 carbon        atoms. It is preferred that one or both aryl groups be        substituted, e.g. mono-alkylated diphenylamine, di-alkylated        diphenylamine, or mixtures of mono- and di-alkylated        diphenylamines.

The diarylamines used in this invention can be of a structure other thanthat shown in the above formula that shows but one nitrogen atom in themolecule. Thus the diarylamine can be of a different structure providedthat at least one nitrogen has 2 aryl groups attached thereto, e.g. asin the case of various diamines having a secondary nitrogen atom as wellas two aryl groups bonded to one of the nitrogen atoms.

The diarylamines used in this invention should be soluble in theformulated crankcase oil package. Examples of some diarylamines that maybe used in this invention include: diphenylamine; various alkylateddiphenylamines; 3-hydroxydiphenylamine; N-phenyl-1,2-phenylenediamine;N-phenyl-1,4-phenylenediamine; monobutyldiphenylamine;dibutyldiphenylamine; monooctyldiphenylamine; dioctyldiphenylamine;monononyldiphenylamine; dinonyldiphenylamine;monotetradecyldiphenylamine; ditetradecyldiphenylamine;phenyl-alpha-naphthylamine; monooctyl phenyl-alpha-naphthylamine;phenyl-beta-naphthylamine; monoheptyldiphenylamine;diheptyldiphenylamine; p-oriented styrenated diphenylamine; mixedbutyloctyldiphenylamine; and mixed octylstryryldiphenylamine, andmixtures thereof. Examples of commercial diarylamines include, forexample, Irganox L06, Irganox L57 and Irganox L67 from Ciba SpecialtyChemicals; Naugalube AMS, Naugalube 438, Naugalube 438R, Naugalube 438L,Naugalube 500, Naugalube 640, Naugalube 680, and Naugard PANA fromCrompton Corporation; Goodrite 3123, Goodrite 3190X36, Goodrite 3127,Goodrite 3128, Goodrite 3185X1, Goodrite 3190X29, Goodrite 3190X40,Goodrite 3191 and Goodrite 3192 from Noveon Specialty Chemicals; VanlubeDND, Vanlube NA, Vanlube PNA, Vanlube SL, Vanlube SLHP, Vanlube SS,Vanlube 81, Vanlube 848, and Vanlube 849 from R. T. Vanderbilt CompanyInc.

IV. Evaluation of Passenger Car Engine Oils in the Micro-Oxidation Test

Preparation of Additized Test Oils

Passenger car engine oils were blended as described in Table 1. Thepreblend used was a 5W-30 passenger car engine oil formulated in GroupII basestock containing 500 ppm of phosphorus derived from ZDDP,detergents, dispersants, pour point depressants and viscosity indeximprovers but no supplemental ashless antioxidants. The alkylateddiphenylamine used was HiTEC® 4793 additive, a styryl octyl alkylateddiphenylamine available from Ethyl Corporation. The tetradecyldiphenylamine used was obtained from the R. T. Vanderbilt Company.Molybdenum compound M-1 was HiTEC® 4716 additive, an organomolybdenumcomplex available from Ethyl Corporation containing approximately 8.0wt. % molybdenum. Molybdenum compound M-2 was Sakura-lube 165, amolybdenum dithiocarbamate available from Asahi Denka Kogyo K. K.containing approximately 4.5 wt. % molybdenum. Molybdenum compound M-3was an experimental organomolybdenum complex prepared at EthylCorporation containing approximately 8.2 wt. % molybdenum. Molybdenumcompound M-4 was an experimental organomolybdenum complex prepared atEthyl Corporation containing approximately 8.3 wt. % molybdenum. Thecalcium phenate used was LZ-6499 available from Lubrizol Corporation andcontained approximately 8.9 wt. % calcium, 3.3 wt. % sulfur, and had atotal base number (TBN) of 247 mg KOH/g. The tetradecylphenothiazineused was an experimental product prepared from thetetradecyldiphenylamine at Ethyl Corporation and contained approximately8.9 wt. % sulfur and 2.7 wt. % nitrogen. The process oil used was a 100Nparaffinic process oil. The components were blended into the preblend at50 C. for approximately 3 hours and cooled.

Evaluation of Additized Test Oils for Deposit Control

The Micro-Oxidation Test is a commonly used technique for evaluating thedeposit forming tendencies of a wide variety of passenger car and diesellubricants as well as mineral and synthetic basestocks. The testmeasures the oxidative stability and deposit forming tendencies oflubricants under high temperature thin-film oxidation conditions. Theability to easily vary test conditions and the flexibility of presentingtest results makes it a valuable research tool for screening a widevariety of lubricant products.

In this test, a thin-film of finished oil is accurately weighed onto anindented low carbon steel sample holder sitting in a glass impingertube. The sample, coupon and impinger tube assembly is then immersed ina high temperature bath. Dry air is passed, at a specific rate, throughthe impinger tube, over the oil sample, and out of the impinger tube tothe atmosphere. At specific time intervals the carbon steel sampleholders are removed from the high temperature bath, rinsed with solventto remove any remaining oil, and oven dried. The solvent washes arefiltered to collect any deposits that dislodge from the carbon steelholders. The sample holders and collected deposits are weighed todetermine the amount of deposit formed at the sampling interval. Resultsare reported as the percent of oil forming deposit at a specific timeinterval. The induction time to deposit formation can also be determinedby calculating the intercept between the baseline formed where minimaldeposits are seen, and the slope formed where a rapid rise in depositformation is seen. Longer induction times correspond to improved depositcontrol. Another parameter of value in this test is the PerformanceIndex (PI). The performance index represents the reduction in depositformation of the additized finished oil over the entire sampling rangeof testing versus the baseline finished oil over the same samplingrange. The formula for calculating PI is as follows:PI=[((area of baseline oil/area of additized oil)−1)×100]

A larger Performance Index (PI) corresponds to improved deposit control.

The test conditions used to evaluated the additized test oils were asfollows: gas dry air, flow-20 cc/minute, temperature 230 C., samplinginterval=50, 60, 70, 80, 90, 100, 110, 120 minutes, samplesize-approximately 20 microL accurately weighed.

The deposit control results are shown in Table 1. The results showconsistently that with all molybdenum additive types, the combination ofmolybdenum and alkylated phenothiazine (Oils 8, 9, 10, and 11) iseffective at improving deposit control relative to oils not containingboth molybdenum and alkylated phenothiazine. Oils containing onlymolybdenum (Oils 2, 3 and 4), or only alkylated phenothiazine (Oil 5),or only tetradecyldiphenylamine (Oil 6), are less effective atcontrolling deposits. The oil containing molybdenum andtetradecyldiphenylamine (Oil 7) is also less effective at controllingdeposits, indicating that the tetradecylphenothiazine/molybdenumcombination is unique for controlling deposits. Oil 12 is an example ofthe deposit control technology disclosed in U.S. Pat. No. 6,174,842.Note that the inventive combination of molybdenum compound M-3 andalkylated phenothiazine affords improved deposit control over theresults from Oil 12 obtained from the technology disclosed in U.S. Pat.No. 6,174,842. TABLE 1 Evaluation Of Crankcase Lubricants For DepositControl Oil Number Oil #1 Oil #2 Oil #3 Oil #4 Oil #5 Oil #6 Oil #7 Oil#8 Oil #9 Oil #10 Oil #11 Oil #12* Crankcase Oil Composition Preblendwt. % 97.30 97.30 97.30 97.30 97.30 97.30 97.30 97.30 97.30 97.30 97.3097.30 Alkylated diphenylamine wt. % 0.70 0.70 0.70 0.70 0.70 0.70 0.700.70 0.70 0.70 0.70 0.70 Tetradecyl wt. % 0.40 0.40 diphenylamineMolybdenum content ppm 160 160 160 160 160 160 160 160 160 Molybdenumcontent wt. % 0.20 0.36 0.20 0.20 0.20 0.36 0.20 0.20 0.20 MolybdenumType M-1 M-2 M-3 None None M-3 M-1 M-2 M-3 M-4 M-3Tetradecylphenothiazine wt. % 0.40 0.40 0.40 0.40 0.40 Calcium Phenatewt. % 0.40 Process Oil wt. % 2.00 1.80 1.64 1.80 1.60 1.60 1.40 1.401.24 1.40 1.40 1.40 TEOST MHT-4 Results Total Deposits mg 62.2 41.1 60.240.1 39.9 31.9 31.2 58.1 CMOT Results Percent Deposits  50 min wt. %10.28 6.25 6.31 12.40 5.95 8.08 9.06 1.54 2.28 1.26 2.72 2.28  60 minwt. % 11.07 6.33 6.59 12.42 5.98 11.70 9.09 5.79 3.00 1.28 3.38 2.38  70min wt. % 17.20 6.89 12.11 12.45 12.11 16.52 15.75 5.82 4.14 2.18 3.613.20  80 min wt. % 19.12 19.95 14.55 21.14 14.51 21.80 17.07 4.76 9.782.18 3.99 8.40  90 min wt. % 22.67 22.75 16.56 24.01 15.65 24.30 21.4518.05 11.21 6.76 7.82 14.68 100 min wt. % 26.77 27.16 19.12 23.98 18.3329.43 23.53 18.84 14.09 8.74 11.66 16.93 110 min wt. % 29.26 27.98 28.2924.09 31.95 36.27 28.60 20.56 22.41 8.74 11.77 18.64 120 min wt. % 32.6625.09 28.13 24.07 30.00 34.10 24.62 23.77 21.15 8.54 11.97 26.64 OnsetTo Deposit Formation min 55 70 59 68 61 <50 57 78 70 79 80 68Performance Index [((area No Mo/area plus Mo) − 1) × 100] PI 0 19 28 926 −7 13 71 92 326 197 81M-1—HiTEC 4716 organomolybdenum complex from Ethyl Corporation (8.0 wt.% Mo)M-2—Sakura-Lube 165 molybdenum dithiocarbamate from Asahi Denka Kogyo K.K. (4.5 wt. % Mo)M-3—X-10826LC Experimental Organomolybdenum from Ethyl Corporatlon (8.2wt. % Mo)M-4—X-10826LC Experimental Organomolybdenum from Ethyl Corporation (8.3wt. % Mo)Alkylated Diphenylamine—HITEC 7190 from Ethyl CorporationCalcium Phenate—LZ-6499 From Lubrizol CorporationTetradecylphenothiazine—Reaction product of tetradecyl diphenylamine andelemental sulfurTetradecyl Diphenylamine—Obtained from R. T. Vanderbilt Chemical Company*Indicates deposit control technology disclosed In U.S. Pat. No.6,174,842

Evaluation of Passenger Car Engine Oils in the Thermo-Oxidation EngineOil Simulation Test (TEOST MHT-4)

The TEOST MHT-4 is a standard lubricant industry test for the evaluationof the oxidation and carbonaceous deposit-forming characteristics ofengine oils. The test is designed to simulate high temperature depositformation in the piston ring belt area of modern engines. The testutilizes a patented instrument (U.S. Pat. No. 5,401,661 and U.S. Pat.No. 5,287,731) with the MHT-4 protocol being a relatively newmodification to the test. Details of the test operation and specificMHT-4 conditions have been published by Selby and Florkowski in a paperentitled, “The Development of the TEOST Protocol MHT as a Bench Test ofEngine Oil Piston Deposit Tendency,” presented a the 12^(th)International Colloquium Technische Akademie Esslingen, Jan. 11-13,2000, Wilfried J. Bartz editor.

Oils #4 through $10 and #12 were evaluated in the TEOST MHT-4 with theresults shown in Table 1. Note that oils containingtetradecylphenothiazine and molybdenum (Oils #8, 9, and 10) showedimproved deposit control versus the corresponding molybdenum compoundalone (Oil #4), tetradecylphenothiazine alone (Oil #5),tetradecyldiphenylamine alone (Oil #6), and a combination oftetradecyldiphenylamine and molybdenum (Oil #7).

Evaluation of Passenger Car Engine Oils in the Hot Oil Oxidation Test

Oils #1, #5 and #10 were evaluated for oxidative stability in the HotOil Oxidation Test. In this test 25.0 grams of the test oil is treatedwith an iron(III)naphthenate catalyst to deliver approximately 250 ppmoil soluble iron to the test oil. The test oil is oxidized in a testtube by bubbling dry air through the oil at a specific rate (10 L/hour)and temperature (160 C.) and for a specific time period. At various timeintervals (24, 32, 48, 56, 72, 80 hours) the oxidized oil is removedfrom the test apparatus and analyzed for viscosity at 40 C. The percentviscosity increase (PVI) of the oxidized oil (Ox) versus the fresh oilwithout catalyst (Fresh) is determined using the following formula: PVI@ 40 C.=((40 C. viscosity Ox-40 C.viscosity Fresh)/(40 C. viscosityFresh))×100.

An increase in PVI corresponds to an increase in the rate of oiloxidation. The Hot Oil Oxidation Test results are shown in Table 2. Notethat the combination of alkylated phenothiazine and molybdenum in oil#10 affords excellent oxidation control versus the lower performance ofoil with only alkylated phenothiazine (#5) or the oil with no alkylatedphenothiazine and no molybdenum (#1). TABLE 2 Evaluation Of CrankcaseLubricants in the Hot Oil Oxidation Test Time Time (min) Oil #1 Oil #5Oil #10 24 h % vis. inc. −29.5 −30.6 −28.8 32 h % vis. inc. −12.2 −30.1−28.2 48 h % vis. inc. 89.3 −29.4 −28.0 56 h % vis. inc. 190.7 −21.0−25.5 72 h % vis. inc. 4134.9 34.9 −23.6 80 h % vis. inc. TVTM 82.3−22.8TVTM = Too viscous to measure

This invention is susceptible to considerable variation in its practice.Accordingly, this invention is not limited to the specificexemplifications set forth hereinabove. Rather, this invention is withinthe spirit and scope of the appended claims, including the equivalentsthereof available as a matter of law.

Also, numerous patents have been identified herein. Those patents areincorporated herein by reference as if set forth in their entirety.

The patentee does not intend to dedicate any disclosed embodiments tothe public, and to the extend any disclosed modifications or alterationsmay not literally fall within the scope of the claims, they areconsidered to be part of the invention under the doctrine ofequivalents.

1. A lubricating composition comprising a major amount of lubricatingoil, and a minor amount of an oil soluble secondary diarylamine, an oilsoluble molybdenum compound provided that said oil soluble molybdenumcompound is not a tri-nuclear molybdenum compound, and an oil solublealkylated phenothiazine.
 2. The lubricating composition as described inclaim 1, wherein the diarylamine comprises an alkylated diphenylamine.3. The lubricating composition as described in claim 2, wherein thealkylated diphenylamine has a concentration of about 0.1 to 2.5 wt. % inthe lubricating composition.
 4. The lubricating composition as describedin claim 3, wherein the alkylated diphenylamine has a concentration ofabout 0.2 to 10.5 wt. % in the lubricating composition.
 5. Thelubricating composition as described in claim 1, wherein the oil solublemolybdenum compound further comprises sulfur.
 6. The lubricatingcomposition as described in claim 1, wherein the oil soluble molybdenumcompound has a concentration sufficient to provide about 20 to 1000 ppmof molybdenum in the lubricating composition.
 7. The lubricatingcomposition as described in claim 6, wherein the oil soluble molybdenumcompound has a concentration sufficient to provide about 20 to 200 ppmof molybdenum in the lubricating composition.
 8. The lubricatingcomposition as described in claim 1, wherein the oil soluble alkylatedphenothiazine has a concentration of about 0.05 to 1.5 wt % in thelubricating composition.
 9. The lubricating composition as described inclaim 8, wherein the oil soluble alkylated phenothiazine has aconcentration of about 0.1 to 1.0 wt. % in the lubricating composition.10. The lubricating composition as described in claim 1, wherein atleast one of the alkyl groups of the alkylated phenothiazine comprisesfrom four to about twenty-four carbon atoms.
 11. The lubricatingcomposition as described in claim 1, wherein the alkylated phenothiazineis disubstituted, with each substituted alkyl group comprising from fourto about twenty-four carbon atoms.
 12. The lubricating composition asdescribed in claim 11, wherein each substituted alkyl group on thealkylated phenothiazine comprises four to, but including, eight carbonatoms.
 13. The lubricating composition as described in claim 1, whereinthe alkylated phenothiazine comprises dioctylphenothiazine.
 14. Thelubricating composition as described in claim 1, wherein the alkylatedphenothiazine comprises monooctylphenothiazine.
 15. The lubricatingcomposition as described in claim 1, wherein the alkylated phenothiazinecomprises dinonylphenothiazine.
 16. The lubricating composition asdescribed in claim 1, wherein the alkylated phenothiazine comprisesmonononylphenothiazine.
 17. The lubricating composition as described inclaim 1, wherein the alkylated phenothiazine comprises mono C₁₄alkylphenothiazine.
 18. The lubricating composition as described inclaim 1, wherein the alkylated phenothiazine comprises di C₁₄alkylphenothiazine.
 19. A lubricating composition comprising a majoramount of lubricating oil, an oil soluble molybdenum compound providedthat said oil soluble molybdenum compound is not a tri-nuclearmolybdenum compound, and an oil soluble alkylated phenothiazine.
 20. Thelubricating composition as described in claim 19, wherein the oilsoluble molybdenum compound further comprises sulfur.
 21. Thelubricating composition as described in claim 19, wherein the oilsoluble molybdenum compound has a concentration sufficient to provideabout 20 to about 1000 ppm of molybdenum in the lubricating composition.22. The lubricating composition as described in claim 21, wherein theoil soluble molybdenum compound has a concentration sufficient toprovide about 20 to about 200 ppm of molybdenum in the lubricatingcomposition.
 23. The lubricating composition as described in claim 19,wherein the oil soluble alkylated phenothiazine has a concentration ofabout 0.05 to 1.5 wt. % in the lubricating composition.
 24. Alubricating composition as described in claim 23, wherein the oilsoluble alkylated phenothiazine has a concentration of about 0.1 to 1.0wt. % in the lubricating composition.
 25. A lubricating composition asdescribed in claim 19, wherein at least one of the alkyl groups of thealkylated phenothiazine comprises from four to about twenty-four carbonatoms.
 26. The lubricating composition as described in claim 19, whereinthe alkylated phenothiazine is disubstituted, with each substitutedalkyl group comprising from about four to about twenty-four carbonatoms.
 27. The lubricating composition as described in claim 19, whereineach substituted alkyl group has four to, but including, eight carbonatoms.
 28. A lubricating composition as described in claim 19, whereinthe alkylated phenothiazine comprises dioctylphenothiazine.
 29. Thelubricating composition as described in claim 19, wherein the alkylatedphenothiazine comprises monooctylphenothiazine.
 30. The lubricatingcomposition as described in claim 19, wherein the alkylatedphenothiazine comprises dinonylphenothiazine.
 31. The lubricatingcomposition as, described in claim 19, wherein the alkylatedphenothiazine comprises monononylphenothiazine.
 32. The lubricatingcomposition as described in claim 19, wherein the alkylatedphenothiazine comprises mono C₁₄ alkylphenothiazine.
 33. The lubricatingcomposition as described in claim 19, wherein the alkylatedphenothiazine comprises di C₁₄ alkylphenothiazine.
 34. A lubricatingcomposition additive comprising an oil soluble secondary diarylamine, anoil soluble molybdenum compound provided that said oil solublemolybdenum compound is not a tri-nuclear molybdenum compound, and an oilsoluble alkylated phenothiazine.
 35. The lubricating compositionadditive as described in claim 34, wherein the diarylamine is analkylated diphenylamine.
 36. The lubricating composition additive asdescribed in claim 34, wherein the oil soluble molybdenum compoundfurther comprises sulfur.
 37. A lubricating composition additive asdescribed in claim 34, wherein the oil soluble molybdenum compound has aconcentration sufficient to provide about 20 to 1000 ppm of molybdenumin the lubricating composition.
 38. The lubricating composition additiveas described in claim 34, wherein the oil soluble molybdenum compoundhas a concentration sufficient to provide about 20 to 200 ppm ofmolybdenum in the lubricating composition.
 39. A lubricating compositionadditive as described in claim 34, wherein at least one of the alkylgroups of the alkylated phenothiazine comprises from four to abouttwenty-four carbon atoms.
 40. The lubricating composition additive asdescribed in claim 34, wherein the alkylated phenothiazine isdisubstituted, with each substituted alkyl group comprising from aboutfour to about twenty-four carbon atoms.
 41. The lubricating compositionadditive as described in claim 40, wherein each substituted alkyl groupcomprises four to, but including, eight carbon atoms.
 42. Thelubricating composition additive as described in claim 34, wherein thealkylated phenothiazine comprises dioctylphenothiazine.
 43. Thelubricating composition additive as described in claim 34, wherein thealkylated phenothiazine comprises monooctylphenothiazine.
 44. Thelubricating composition additive as described in claim 34, wherein thealkylated phenothiazine comprises dinonylphenothiazine.
 45. Thelubricating composition additive as described in claim 34, wherein thealkylated phenothiazine comprises monononylphenothiazine.
 46. Thelubricating composition additive as described in claim 34, wherein thealkylated phenothiazine comprises mono C₁₄ alkylphenothiazine.
 47. Thelubricating composition additive as described in claim 34, wherein thealkylated phenothiazine comprises di C₁₄ alkylphenothiazine.
 48. Alubricating composition additive comprising an oil soluble molybdenumcompound provided that said oil soluble molybdenum compound is not atri-nuclear molybdenum compound and an oil soluble alkylatedphenothiazine.
 49. The lubricating composition additive as described inclaim 48, wherein the oil soluble molybdenum compound further comprisessulfur.
 50. The lubricating composition additive as described in claim48, wherein at least one of the alkyl groups of the alkylatedphenothiazine comprises from four to about twenty-four carbon atoms. 51.The lubricating composition additive as described in claim 48, whereinthe alkylated phenothiazine is disubstituted, with each substitutedalkyl group comprising from about four to about twenty-four carbonatoms.
 52. The lubricating composition additive as described in claim51, wherein each substituted alkyl group comprises four to, butincluding, eight carbon atoms.
 53. The lubricating composition additiveas described in claim 48, wherein the alkylated phenothiazine comprisesdioctylphenothiazine.
 54. The lubricating composition additive asdescribed in claim 48, wherein the alkylated phenothiazine comprisesmonoctylphenothiazine.
 55. The lubricating composition additive asdescribed in claim 48, wherein the alkylated phenothiazine comprisesdinonylphenothiazine.
 56. The lubricating composition additive asdescribed in claim 48, wherein the alkylated phenothiazine comprisesmonononylphenothiazine.
 57. The lubricating composition additive asdescribed in claim 48, wherein the alkylated phenothiazine comprisesmono C₁₄ alkylphenothiazine.
 58. The lubricating composition additive asdescribed in claim 48, wherein the alkylated phenothiazine comprises diC₁₄ alkylphenothiazine.
 59. A method for improving the antioxidancyand/or anti-wear properties of a lubricating composition comprisingincluding in the lubricating composition an oil soluble molybdenumcompound provided that said oil soluble molybdenum compound is not atri-nuclear molybdenum compound and an oil soluble alkylatedphenothiazine.
 60. The method as described in claim 59, furthercomprising including in the lubricating composition an oil solublesecondary diarylamine.
 61. The method as described in claim 60, whereinthe diarylamine is an alkylated diphenylamine.
 62. The method asdescribed in claim 60, wherein the secondary diarylamine has aconcentration of about 0.1 to 2.5 wt. % in the lubricating composition.63. The method as described in claim 60, wherein the secondarydiarylamine has a concentration of about 0.2 to 1.5 wt. % in thelubricating composition.
 64. The method as described in claim 59,wherein the oil soluble molybdenum compound further comprises sulfur.65. The method as described in claim 59, wherein the oil solublemolybdenum compound has a concentration sufficient to provide about 20to about 1000 ppm of molybdenum in the lubricating composition.
 66. Themethod as described in claim 65, wherein the oil soluble molybdenumcompound has a concentration sufficient to provide about 20 to 200 ppmof molybdenum in the lubricating composition.
 67. The method asdescribed in claim 59, wherein the oil soluble alkylated phenothiazinehas a concentration of about 0.05 to 1.5 wt. % in the lubricatingcomposition.
 68. The method as described in claim 67, wherein the oilsoluble alkylated phenothiazine has a concentration of about 0.1 to 1.0wt. % in the lubricating composition.
 69. The method as described inclaim 59, wherein at least one of the alkyl groups of the alkylatedphenothiazine comprises from four to about twenty-four carbon atoms. 70.The method as described in claim 59, wherein the alkylated phenothiazineis disubstituted, with each substituted alkyl group comprising fromabout four to about twenty-four carbon atoms.
 71. The method asdescribed in claim 70, wherein each substituted alkyl group has four tobut including eight carbon atoms.
 72. The method as described in claim59, wherein the alkylated phenothiazine comprises dioctylphenothiazine.73. The method as described in claim 59, wherein the alkylatedphenothiazine comprises monooctylphenothiazine.
 74. The method asdescribed in claim 59, wherein the alkylated phenothiazine comprisesdinonylphenothiazine.
 75. The method as described in claim 59, whereinthe alkylated phenothiazine comprises monononylphenothiazine.
 76. Themethod as described in claim 59, wherein the alkylated phenothiazinecomprises mono C₁₄ alkylphenothiazine.
 77. The method as described inclaim 59, wherein the alkylated phenothiazine comprises di C₁₄alkylphenothiazine.
 78. The method as described in claim 59, furthercomprising including in the lubricating composition an oil solublealkylated diphenylamine, an oil soluble phosphorus compound, and an oilsoluble hindered phenolic derived from 2,6-di-tert-butylphenol.
 79. Themethod as described in claim 59, further comprising including in thelubricating composition an oil-soluble alkylated diphenylamine, an oilsoluble phosphorus, and an oil soluble calcium-containing detergent. 80.A method for lubricating an engine, comprising lubricating said enginewith a lubricating composition of claim
 1. 81. A method for lubricatingan engine, comprising lubricating said engine with a lubricatingcomposition of claim
 19. 82. A method for lubricating an engine,comprising lubricating said engine with a lubricant containing thelubricant composition additive of claim
 34. 83. A method for lubricatingan engine, comprising lubricating said engine with a lubricantcontaining the lubricant composition additive of claim
 48. 84. Thecomposition of claim 1, wherein the composition comprises zerophosphorus.
 85. The composition of claim 1, wherein the compositioncomprises essentially zero phosphorus.
 86. The composition of claim 19,wherein the composition comprises zero phosphorus.
 87. The compositionof claim 19, wherein the composition comprises essentially zerophosphorus.
 88. The composition of claim 34, wherein the compositioncomprises zero phosphorus.
 89. The composition of claim 34, wherein thecomposition comprises essentially zero phosphorus.